Ceramic matrix composite

ABSTRACT

A novel ceramic matrix composite is disclosed for forming components that are operable in high temperature environments such those in gas turbine engines and the like. The ceramic matrix composite can include at least one layer of non-crimped fibers positioned substantially parallel to one another. A relatively small diameter elastic fiber can be constructed to stitch the non-crimped fibers together and a ceramic matrix may be deposited around the at least one layer of non-crimped fibers.

CROSS REFERENCE

The present application is a divisional application of, and claimspriority under 35 U.S.C. §121 to U.S. patent application Ser. No.14/097,857, “Ceramic Matrix Composite”, filed Dec. 5, 2013, which is anon-provisional application of, and which claims priority to U.S.Provisional Patent Application No. 61/786,304, “Ceramic MatrixComposite”, filed Mar. 15, 2013, both of which are incorporated byreference in their entirety.

FIELD OF THE INVENTION

The present disclosure relates to ceramic matrix composite fabricationand more particularly, to a ceramic matrix composite having improvedmaterial properties for fabricating components that are operational ingas turbine engines and the like.

BACKGROUND

Gas turbine engines operate at temperatures that are higher than themelting temperature of many of the metal components used in the hotareas such as the combustor and turbine sections. Large amounts ofworking fluid must be diverted from making power in the gas turbineengine to cooling metal components to keep the temperatures low enoughthat the integrity of the components are maintained in the hot operatingenvironment. Ceramic based materials have been used for some of thesecomponents because of their low weight and higher temperature capabilityrelative to metal based materials. Some components made of ceramicmatrix composite material have drawbacks due to strength limitations,other shortcomings, and disadvantages relative to certain applications.Accordingly, there remains a need for further contributions in this areaof technology.

SUMMARY

One embodiment of the present disclosure includes a unique ceramicmatrix composite fabrication for high temperature applications. Anotherembodiment includes a gas turbine engine having a component made fromthe unique ceramic matrix fabrication. Other embodiments include uniqueapparatuses, systems, devices, hardware, methods, and combinations foran improved ceramic matrix composite construction. Further embodiments,forms, features, aspects, benefits, and advantages of the presentapplication shall become apparent from the following description anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The description herein makes reference to the accompanying drawingswherein like reference numerals refer to like parts throughout theseveral views, and wherein:

FIG. 1 is a schematic cross-sectional side view of a turbofan enginehaving components made from a ceramic matrix composite according to anembodiment of the present disclosure;

FIG. 2 is a perspective view of a representative ceramic matrixcomposite component in the form of a vane segment according to anembodiment of the present disclosure;

FIG. 3 is a perspective view of another representative ceramic matrixcomposite component in the form of a turbine blade according to anembodiment of the present disclosure;

FIG. 4 is a schematic representation of a ceramic matrix composite layerhaving a crimped fiber weave according to a prior art configuration;

FIG. 5 is a schematic representation of a ceramic matrix composite layerhaving a non-crimped fiber pattern according to an embodiment of thepresent disclosure;

FIG. 6 is a schematic representation of a 3-ply ceramic matrix compositelaminate having a non-crimped fiber pattern according to an embodimentof the present disclosure; and

FIG. 7 is a flow chart illustrating a method of forming a component withceramic matrix composite having a non-crimped fiber pattern according toan embodiment of the present disclosure.

DETAILED DESCRIPTION

For purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings, and specific language will be used to describe the same.It will nonetheless be understood that no limitation of the scope of theinvention is intended by the illustration and description of certainembodiments of the invention. In addition, any alterations and/ormodifications of the illustrated and/or described embodiment(s) arecontemplated as being within the scope of the present invention.Further, any other applications of the principles of the invention, asillustrated and/or described herein, as would normally occur to oneskilled in the art to which the invention pertains, are contemplated asbeing within the scope of the present invention.

Referring to FIG. 1, a schematic view of a gas turbine engine configuredas a turbofan engine 10 is depicted. While the turbofan engine 10 isillustrated in simplistic schematic form, it should be understood thatthe present disclosure including a component formed from a novel ceramicmatrix composite is not limited to any particular engine design orconfiguration and as such may be used with any form of gas turbineengine such as turboprops, turbojets, unducted fan engines, and othershaving a range of complexities including multiple spools (multipleturbines operationally connected to multiple compressors), variablegeometry turbomachinery, and in commercial or military applications.Further the novel ceramic matrix composite defined by the presentdisclosure can be used in other systems that operate in environmentswherein high temperature capable components having a high strength toweight ratio is advantageous to operational capability.

The turbofan engine 10 will be described generally as one embodiment ofthe present disclosure, however significant details regarding gasturbine engine design and operation will not be presented herein as itis believed that the theory of operation and general parameters of gasturbine engines are well known to those of ordinary skill in the art.The turbofan engine 10 includes an inlet section 12, a fan section 13, acompressor section 14, a combustor section 16, a turbine section 18, andan exhaust section 20. In operation, air illustrated by arrows 22 isdrawn in through the inlet 12 and passes through at least one fan stage24 of the fan section 13 where the ambient air is compressed to a higherpressure. After passing through the fan section 13, the air can be splitinto a plurality of flowstreams. In this exemplary embodiment, theairflow is spilt into a bypass duct 26 and a core passageway 28. Airflowthrough the bypass duct 26 and the core passageway 28 is illustrated byarrows 30 and 32 respectively. The bypass duct 26 encompasses the corepassageway 28 and can be defined by an outer circumferential wall 34 andan inner circumferential wall 36. The bypass duct 26 can also include abypass nozzle 42 operable for creating a pressure differential acrossthe fan 24 and for accelerating the bypass airflow 30 to provide bypassthrust for the turbofan engine 10.

The core airflow 32 enters the core passageway 28 after passing throughthe fan section 13. The core airflow is then further compressed in thecompressor section 14 to a higher pressure relative to both ambientpressure and the air pressure in the bypass duct 26. The air is mixedwith fuel in the combustor section 16 wherein the fuel/air mixture burnsand produces a high temperature working fluid from which the turbinesection 18 extracts power. The turbine section 18 can include lowpressure turbine 50 mechanically coupled to the fan section 13 through alow pressure shaft 52 and a high pressure turbine 54 mechanicallycoupled to the compressor section 14 through a high pressure shaft 56.The shafts 52, 56 rotate about a centerline axis 60 that extends axiallyalong the longitudinal axis of the engine 10, such that as the turbinesection 18 rotates due to the forces generated by the high pressureworking fluid, the fan section 13 and compressor section 14 section arerotatingly driven by the turbine section 18 to produce compressed air.After passing through the turbine section 18, the core exhaust flowrepresented by arrow 62 is accelerated to a high velocity through a coreexhaust nozzle 64 to produce thrust for the turbofan engine 10.

Referring now to FIG. 2, a vane segment 100 is illustrated as anexemplary component made from a ceramic matrix composite fabricationaccording to the present disclosure as will be described in detailbelow. The vane segment 100 can include an outer end wall 110 and aninner end wall 112 proximate a tip and a hub respectively of a vane 114.The end walls 110, 112 can be configured to operably connect withsupport structure (not shown) of the engine 10. A plurality of outletcooling holes 116 can be formed along the outer surface of the vane 114and the end walls 110, 112 to eject cooling fluid 120 from the vanesegment 100 and into a hot fluid flowpath 119. The hot fluid flowpath119 can be bounded by the outer vane end wall 110 and the inner vane endwall 112. High temperature fluid such as exhaust gas from a combustionsection as illustrated by arrow 122 can flow through the hot fluidflowpath 119 and transfer heat into the vane segment 100. Cooling fluid120, such as air or the like can be provided to the vane segment 100, byway of example and not limitation through an inlet aperture or aplurality of inlet cooling holes 118 formed in one or both of the endwalls 110, 112.

Referring now to FIG. 3, a turbine blade is depicted as anotherexemplary component that may be made from a ceramic matrix compositematerial according to the present disclosure. The turbine blade 200 caninclude a platform 202 that may have an airfoil 204 extending radiallyoutward therefrom. A root section 206 can include dovetail shapedconnecting portion extending radially inward from the platform 202. Theturbine blade 200 may also have other features such as cooling holes 208and one or more layers of coatings such as a thermal barrier coatingand/or an environmental barrier coating and the like.

Prior art fiber layers woven into fabrics have crimped fibers such thatthe fibers are intertwined or alternating above and below adjacentfibers in a weave fashion as illustrated in FIG. 4. A multi-layer,crimped ceramic textile 300 includes a first layer of ceramic fibers302, a second layer of ceramic fibers 304, and a third layer of ceramicfibers 306 formed in a weave pattern between adjacent fiber plies. Ascan be seen in FIG. 4, the prior art fibers are interweaved betweenlayers in and out of a layer plane such that each fiber is bent orcrimped as it traverses across another fiber in a weave pattern. Wovenfibers such as those shown in FIG. 4 causes simple tension orcompression forces acting along an axis to generate off axis loads orforces in the fibers. For example, a simple one dimensional tensionforce acting on the textile 300 represented by arrow F1 operates togenerate forces in the fibers that include a more complex pattern due tothe interaction between fibers. The force F1 generates nonlinear loadinginto fiber 304. A force represented by arrow F2 caused by a contactforce with a fiber 306 above the fiber 304 is generally normal to theforce vector F1. A force represented by arrow F3 caused by a contactforce with a fiber 302 below the fiber 304 is generally normal to theforce vector F1 and in opposite direction to that of the force F2. Thefiber 304 will also load along the longitudinal direction thereof asillustrated by the double arrow labeled as F4. The crimp designillustrated in FIG. 4 results in an off axis loading and non-uniformload distribution within each fiber of a laminate layer. Fabrication andapplication of non-woven textiles in ceramic matrix compositeapplications can improve the tensile response of the material.

Referring now to FIG. 5, a schematic representation of a preform ply orlayer 400 having a plurality of non-crimped fibers 402 is shown therein.Each of the plurality of non-crimped fibers 402 is positioned insubstantially parallel orientation relative to one another. Thenon-crimped fibers 402 can extend from a first end 404 to a second end406 of the preform layer 400 in a substantially longitudinal fashion.The non-crimped fibers 402 do not cross over or around one another alonga longitudinal length of the fibers 402 between the first and secondends, 404, 406 respectively such that in plane reaction forces will actalong a longitudinal length of the fibers 402. For example, asubstantially planer force represented by a double arrow F1 acting intension or compression on the preform layer 400 will cause asubstantially longitudinal reaction force represented by a double arrowF2 in each of the non-crimped fibers 402 positioned in the layer 400 inthe planer configuration. The non-crimped fibers 402 may be made from anumber of materials including but not limited to ceramic material,organic material, metallic material, and/or glass material.

In order to hold the plurality of non-crimped fibers in a desiredposition relative to one another, small fiber 408 may be used to stitchthe non-crimped fibers together. In one form the small fiber 408 may beused to stitch together the relatively larger non-crimped ceramic fibers402. In another form, the small fiber may be made of an elastic polymermaterial and are configured or stitched in a manner as to provide adesired tow configuration as a portion of a preform structure. The smallfiber 408 can be bent at a sharp radius relative the diameter of thesmall fiber 408, and can also be stretched and twisted so as to hold thenon-crimped fibers 402 in position to form a complex preform structure.

The small fiber 408 may be made from a number of different materialsincluding, but not limited to a polymer material such aspolyvinylalcohol (PVA) that can be dissolved in water, an acrylicmaterial that can be removed by heating in a vacuum with very littleresidual char, and/or a carbon material that can survive the processingto remain in the finished CMC component. Subsequent processing may ormay not include removal of the small fiber 408 from the preform afterlaminating and prior to matrix infiltration of the preform.

The non-crimped fibers 402 can be made from a variety of materialsincluding, but not limited to polymers, ceramics, inter-metallics,certain metals and/or mixtures thereof. Non-crimped ceramic fibers orplies can be made from, but are not limited to carbon, silicon carbides,alumina, and mullite.

The matrix may be formed from any number materials including, but notlimited to polymers, metals, and ceramics and mixtures thereof. In oneexemplary embodiment, a ceramic matrix may include silicon carbideand/or silicon/silicon carbide. The matrix can be combined with thenon-crimped fiber preform via any operable process that allows thematrix material to be infiltrated into the porosity of the coatedpreform such as chemical vapor deposition or chemical vaporinfiltration, pyrolysis, chemical reaction, sintering, andelectrophoresis. In one example, the matrix material can be deposited bya slurry casting or slip casting process followed by melt infiltration.A slurry of carbon, carbon-containing resin, or other carbonaceousmaterial, and optionally silicon carbide particulate is introduced intothe preform porosity and molten silicon is thereafter infiltrated intothe remaining space to react with the carbonaceous material to formsilicon carbide. The amount of silicon may be stoichiometric, so thatthe matrix is silicon carbide. An excess of silicon may instead be used,so that the final structure is a mixture of reacted silicon carbide andunreacted silicon carbide.

Referring now to FIG. 6, a multi-layer laminate 500 made of non-crimpedceramic fibers is shown therein. The multi-layer laminate 500 caninclude a plurality of layers such as the layer of fiber 400 shown inFIG. 5. The multi-layer laminate 500 includes a first layer 502, asecond layer 504, and a third layer 506 in the illustrative embodiment.While three layers are shown in the exemplary embodiment, it should beunderstood that any number of layers may be used to provide structurefor the preform prior to matrix infiltration.

The first layer 502 of the multi-layer laminate 500 includes a pluralityof non-crimped fibers 510 positioned in one direction depicted by arrow511. Each of the non-crimped fibers 510 can include a coating 512applied around the outer surface thereof to provide desirable materialproperties such as friction reduction, strength enhancement or corrosionresistance to name but a few examples. A matrix material 514 can bedeposited and/or infiltrated in and around each of the fibers 510 so asto form a laminate layer of ceramic matrix composite material.

The second layer 504 of the multi-layer laminate 500 can include aplurality of non-crimped fibers 520 positioned in a substantiallyorthogonal orientation represented by arrow 521 relative to theorientation of the fiber 510 of the first layer 502. The non-crimpedfibers 520 of the second layer 502 can also include a coating 522 formedaround the perimeter thereof in a similar manner to fibers 510 of thefirst layer 502. A matrix material 524 can be deposited and/orinfiltrated in and around each of the fibers 520 so as to form alaminate layer of ceramic matrix composite material.

The third laminate layer 506 can include a plurality of non-crimpedfibers 530 oriented in the same general direction as the fibers 510 inthe first layer 502 of the multi-layer laminate 500. In this manner,each layer can include a fiber orientation that can alternateorthogonally 0-90 degrees relative to adjacent layers of the multi-layerlaminate 500. The third layer 506 may also include a coating 532 formedaround each of the non-crimped fibers 530 in similar fashion to thecoatings in the first and second layers 502, 504, respectively. A matrixmaterial 534 can be deposited and/or infiltrated in and around each ofthe fibers 530 so as to form a laminate layer of ceramic matrixcomposite material. While different numbers are used to point out thefibers, coatings and matrix of the various layers, it should beunderstood that the fibers, the coatings and the matrix may be made fromthe same materials in each of the layers.

A plurality of small fibers 408 such as those made from an elasticpolymer material can be used to stitch together the first, second andthird layers, 502, 504, 506 respectively, to create a desired preformconfiguration. In some embodiments, the small fiber stitching 408 may beremoved prior to infiltrating the preform with a ceramic matrix. Inother embodiments the small fiber stitching such as small fiber formedfrom carbon may remain as part of the finished ceramic matrix compositecomponent. A coating such as boron nitride coating can also be depositedon the non-crimped fibers prior to infiltration of a matrix material.The matrix material 514, 524, 534 can then be infiltrated in and aroundthe non-crimped fibers in each of the layers 502, 504, and 506 to formthe multi-layer ceramic matrix composite laminate 500 such that thestrength of the ceramic matrix composite is maximized due to theuni-direction force loading on the non-crimped fibers.

Referring now to FIG. 7, a flowchart depicting an exemplary method forforming a ceramic matrix composite according to the present disclosureis illustrated. The exemplary method starts at step 600. At step 602, aplurality of non-crimped fibers are positioned in a desired orientationand stitched together with relatively small elastic fibers. In oneexemplary embodiment, the non-crimped fibers can be made from a ceramicbased material and the small elastic fibers can be made from a polymermaterial. At step 604, one or more layers of non-crimped ceramic fiberscan be formed into a core preform shape. At step 606, the layers ofnon-crimped ceramic fibers can be coated as desired and laminated in afixed position. At step 608, the small elastic polymer fibers can beremoved from the core preform. Various methods for removing smallelastic fiber are contemplated by the present disclosure. At step 610,the exemplary method includes a ceramic matrix densification process.After depositing ceramic matrix in and around the non-crimped fiberpreform, various curing and finishing processes may be employed such asplacing the CMC component in a temperature controlled and humiditycontrolled atmosphere, finish machining, and/or adding one or morecoatings for thermal and/or environmental protection.

The present disclosure can be at least partially defined by anon-crimped fiber layout or orientation in each layer of ceramic matrixcomposite laminate. The small elastic fibers can be selected to enablesimple removal after the ceramic perform is finalized. The elastic fiberremoval process is designed to be tolerated by the ceramic fibers anddoes not result in leftover residual material that may adversely affectthe ceramic fiber.

The response of the ceramic matrix composite with non-crimped fibers isdifferent than that having woven fibers, because although the stiffnessduring loading will remain the same, the stress level where the matrixcracking begins will be delayed. This value is sometimes referred to asthe proportional limit and is a critical property of a CMC componentdesign. Prior art CMC design using crimped fiber formed fabrics causescomplex inter-laminar tension loading in the ceramic matrix compositecomponent and the nesting configuration is an important design element.In the case of a non-crimped fabric, the interaction of all the layersis more uniform and therefore the nesting design is not a criticalfactor. More consistent inter-laminar properties of the laminate layershaving non-crimped fibers will support higher design stresses.

Another feature of the present disclosure is that the conformability ofthe fabric is enhanced because each unique directional layer ofnon-crimped fiber can be held together by relatively flexible polymerfibers. This is especially useful for ceramic fibers where shear anddrapability are limited by the high stiffness of the fiber. The crimpingof typical fabrics results in local variations of fiber consolidationwhen a laminate is squeezed to the desired fiber volume. The sections ofa tow that are more compressed may result in fiber to fiber contact sothat the interface coating cannot surround each fiber. This can lead toreduced strength because a fracture of the lowest strength fiber in agroup of fibers that are not separated by an interface coatingpropagates to the higher strength fibers. Essentially, the weakest linkresults in multiple failures instead of only one. The local compressionof fiber tows can limit the effectiveness of the matrix densificationprocess. Densification processes such as chemical vapor infiltration(CVI), pre-ceramic polymer infiltration, pyrolysis, slurry and meltinfiltration are affected when fibers are locally compressed togetherand limit the ability for the ceramic matrix material to infiltrate asnecessary between the fibers. This leads to greater variation in themechanical and thermal behavior of the material and effectively reducesthe strength of the CMC component.

Traditional woven fabrics have varying levels of crimps in the towsdepending on the weaving direction. In weave patterns, warp fibers aredefined as the set of lengthwise fibers that are held in tension andweft fibers are defined as the fibers that are inserted over-and-underthe warp fibers. The warp fibers that are in tension typically have lesscrimp than the weft fibers that are un-tensioned. In a prior artlaminate of a 0/90 fabric, the variation in tension and untensionedfibers leads to variation of mechanical properties between the twofibers having a 0/90 orientation. With a non-crimped laminate of thepresent disclosure the difference in mechanical properties between 0/90layers of fabric formed by parallel fiber is substantially eliminated,therefore the fabric can be more efficiently utilized because of theorientation of the textile is far less important than with the prior arttextile. For ceramic fibers, weaving multi-layer textiles is moredifficult because of the stiffness of the fiber which results inlimitations on the minimum bend radius. Whereas, non-crimped textilesuse highly elastic stitching material, therefore multi-layerconstructions are more easily fabricated. This can translate into costsavings in production because fewer discrete layers need to be cut andassembled for a core preform.

In one form, the small elastic fibers used to hold the ceramic fiberstogether may be made of a polymer such as a polyvinyl alcohol (PVA).Small fibers made from PVA can be dissolved in water and thereforerelatively easy to remove from the preform. In another form, the smallelastic fiber may be an acrylic fiber that can be easily removed fromthe preform by heating the preform in a vacuum and pyrolyzing the smallfibers. Pyrolyzing the acrylic fibers leaves only a very small residualchar and does not degrade the ceramic fibers or ceramic matrix. Inanother example, the small fibers can also be a carbon fiber thatsurvives subsequent ceramic processing, but does not degrade the CMCperformance. The small elastic fibers may be woven around a primaryreinforcement or alternatively may be a polymer that holds the fiberstogether like a pre-impregnated textile for creating polymer matrixcomposites. It should be understood that there are no limitations forthe material selection for the small elastic fiber binding material,other than the material must be compatible with the ceramic matrixcomposite and be able to hold the ceramic fibers in a desired corepreform shape during the CMC fabrication process.

A non-crimped fabric may be composed of one or more layers. In someembodiments, each layer may have a different fiber orientation relativeto an adjacent layer, alternatively in other embodiments, adjacentlayers may have the same fiber orientation. The fiber tows, which can bedefined as an untwisted bundle of continuous fibers, may be spread priorto stitching to reduce the layer thickness in a particular direction orto make use of a bundle with a larger fiber count. In one non-limitingexample, the non-crimped textiles may also be use bundles or individualmonofilaments with a diameter from 20 to 300 microns like SCS ultrasilicon carbon manufactured by Specialty Products. In anothernon-limiting example pitch monofilament or boron monofilament may beused with the non-crimped textiles. Because these filaments haverelatively large cross sections they cannot be woven like a traditionaltextile, but can be advantageously utilized in a non-crimped CMC tow.

The increase in microstructural uniformity of the non-crimped fiberlayers will lead to more consistent material behavior and bettermechanical and thermal properties for a component design due to thereduced variation of the non-crimped design. The increased uniformity ofthe microstructure may support an increase in densification rate thatcan reduce the cost of fabricating the ceramic matrix composite.

The non-crimped fiber design also provides additional options forbiasing of the fiber direction. For example, a non-crimped fabric can beconstructed with three layers so that the outer two are in the samedirection and the center is in a perpendicular direction. In otherembodiments, different relative fiber orientations can be used such as0-90-45 (0 degrees-90 degrees-45 degrees). In other examples anyrelative fiber orientation may be fabricated as desired.

Prior art methods of fabrication using a weave can increase fiber volumein a particular direction because of the overlapping of the crimpedfabrics. This can cause a degradation of material properties or atradeoff in final dimensional configuration due to the non-uniformity ofthe weave layers. The methods of biasing in typical fabric constructionswill result in greater non-uniformity of the micro-structure, thereforeusing non-crimped fiber layers has a distinct advantage. The fibervolume of the composite for traditional textiles will reach a limit muchearlier due to the inefficient spacing of the fiber bundles and gaps inthe compressed structure. Further the non-crimped laminate layersincreased proportional strength because the fibers are not positionedoff axis and carry loads in a substantially longitudinal direction.Increased formability of the fabric due to the reduced interaction ofthe layers is provided by using the elastic stitching material andpattern whereas the limits of prior art fabrics construction are fixedby the fabric type, weave style and spacing of the individual tows.

Another improved property of the non-crimped fiber pattern is that thereis additional freedom of fibers to shift relative to one another whichenables a creation of simple bends and cross sections using relativelythick non-woven materials. This is helpful when the stitching design isoptimized for the preform construction and results in a uniform crosssection with simpler construction techniques. Further, an improvedsurface finish can result from utilizing non-crimped fiber layers in aceramic matrix composite because it results in flatter or smootherexternal surfaces relative to the prior art construction using a weavedesign.

In one exemplary embodiment, a CMC structure can include a C-shapedcross section. A ten layer non-woven textile can be fabricated with 35%fiber volume and stitched in place with small elastic fiber. Six layerscan be oriented in a 0 direction while the other four layers can beoriented in the 90° direction. The preform can be shaped by forming itover a male tool as desired. The preform can then be captured by amating tool to fully enclose the inner and outer surfaces of theC-shaped cross section. The preform and tools can be heated in an ovenat, for example 600° C. to remove the small stitching. The preform andtool can be placed in a vacuum furnace and the fibers can be coated withboron nitride via chemical vapor infiltration (CVI). The preform canthen be additionally infiltrated with a silicon carbide (SiC) by CVI.The preform densification is completed by a silicon carbideslurry/silicon melt (SiC slurry/Si) infiltration process. The CMCcomponent can then be finish machined and coated with an environmentalbarrier coating and/or a thermal barrier coating and the like. Theimproved microstructure will reduce manufacturing costs for thepreforming operation and will result in life cycle cost benefits to theCMC component.

In another example, a hollow airfoil shaped vane can be constructed froma SiC/SiC (silicon carbide fiber/silicon carbide matrix) ceramic matrixcomposite for a gas turbine engine or the like. A C-shaped preform canbe constructed using non-woven textiles including an inner layer offiber oriented in a 0 direction and opposing outer layers on each sideof the inner layer formed in a 90° direction relative to the 0direction. A vane inner mandrel can be wrapped so that the 90° directionof the textile is oriented chord-wise relative to the airfoil shapedvane to be formed. This orientation process produces an increasedstrength and stiffness in the chord-wise direction. At least threelayers of the same textile can be employed in a construction of thispreform. The preform can then be captured by a mating tool to fullyenclose the inner and outer surfaces of the C-shaped preform. TheC-shaped preform along with the tools can then be heated in an oven atapproximately 600° C. to remove the small elastic stitching. The preformand tools can then be placed in a vacuum furnace to provide a boronnitride fiber coating to the fibers via CVI. The part can then beadditionally infiltrated by a SiC material through CVI. Ceramiccomposite densification can then be completed with a SiC slurry/Si meltinfiltration process. The component can then be machined and coated withan environmental barrier coating and/or thermal barrier and the like.The improved microstructure and increased strength in the primary loaddirection results in increased design margin and life improvements forthe component.

In yet another non-limiting example, a CMC solid turbine blade preformcan be fabricated according to the teachings of the present disclosure.The blade preform can be fabricated using a Hi-NICALON™ S non-crimpedtextile. Hi-NICALON™ ceramic fiber is a multi-filament siliconcarbide-type fiber manufactured by Nippon Carbon Co., Ltd. (NCK) ofJapan. The textile can be bound together with small PVA thread. Thetextile can then be constructed with a spread Hi-NICALON™ S tow in thechord-wise direction. SCS silicon carbide fibers made be SpecialtyMaterials Inc, including an SCS Ultra Fiber can be mixed into theHi-NICALON™ S tow at a 2:1 ratio by mass in the span wise direction. Theoverall fiber ratio of the span:chord ratio can be approximately 3:1.The textile can be limited to two layers so as to permit fine or smalldetailed features to be formed therein. The layers can be cut andlaminated with a tool to create a desired shape of the preform. Thepreform can then be captured with perforated high temperature tooling.The preform and tool can be soaked in water at 90° C. for approximatelytwo hours to remove the small PVA stitching. This cycle can be repeatedif necessary. The preform and the tool can then be dried in an oven at150° C. as necessary which can take up to four hours or more. Thepreform and tool can then be placed in a vacuum furnace for boronnitride fiber coating via CVI. The component is then additionallyinfiltrated by SiC by CVI. Part densification can be completed by a SiCslurry/Si melt infiltration process to form the ceramic matrix. The partcan then be finished machined and coated as desired with anenvironmental barrier coating and/or a thermal barrier coating and thelike. The textile used to form the exemplary turbine blade results inmaterial properties having high strength and creep resistance such thatthe turbine blade can be used in gas turbine engines that operate athigh speeds and high temperatures.

In one aspect, the present disclosure includes a ceramic matrixcomposite comprising at least one layer of non-crimped fibers positionedsubstantially parallel to one another; a relatively small diameterelastic fiber can be constructed to stitch the non-crimped fiberstogether; and a ceramic matrix deposited around the at least one layerof non-crimped fibers. The small elastic fiber can be made from one of apolymer material, acrylic material and a ceramic material. In one form,the small elastic fiber can be removed from the non-crimped fibers priorto depositing the ceramic matrix. The small elastic fiber removal can beimplemented by exposure to a liquid, exposure to a gas or exposure toheat in a vacuum.

In another aspect, the present disclosure includes a gas turbine enginecomprising a compression section; a combustor section positioneddownstream of the compression section; a turbine section positioneddownstream of the combustor section; an exhaust section positioneddownstream of the turbine section; and a component positioned in one ofthe sections. The component can be formed from a plurality of layers ofnon-crimped fibers, wherein each layer includes a plurality ofnon-crimped fibers positioned substantially parallel to one another. Arelatively small diameter fiber can be constructed to stitch the layersof non-crimped fibers together to form a preform core shape; and aceramic matrix can infiltrated into the preform core shape via CVI toform a non-finished CMC component. The small fiber can be made from oneof a polymer material, acrylic material and a carbon material and insome embodiments may be removed from the preform prior to depositing theceramic matrix. Each of the layers of non-crimped fibers may have thesame fiber orientation or different fiber orientation relative adjacentlayers.

In another aspect, the present disclosure includes a method forstitching plies of relatively large diameter non-crimped fibers togetherwith relative small diameter fiber; forming the plies of non-crimpedfibers into a core preform shape; and infiltrating the core preform witha ceramic matrix to form a non-finished ceramic matrix compositecomponent. The method can further include coating the non-crimped fibersprior to the infiltrating with a material at least partially made fromboron nitride. The method can further include removing the small fiberfrom the preform prior to the infiltrating by exposing the small fiberto at least one of a liquid, a gas or heat in a vacuum. The CMCcomponent can post processed to make a finished component that isoperable in a gas turbine engine.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment(s), but on the contrary, is intended to covervarious modifications and equivalent arrangements included within thespirit and scope of the appended claims, which scope is to be accordedthe broadest interpretation so as to encompass all such modificationsand equivalent structures as permitted under the law. Furthermore itshould be understood that while the use of the word preferable,preferably, or preferred in the description above indicates that featureso described may be more desirable, it nonetheless may not be necessaryand embodiment lacking the same may be contemplated as within the scopeof the invention, that scope being defined by the claims that follow. Inreading the claims it is intended that the words such as “a,” “an,” “atleast one” and “at least a portion” are used, there is no intention tolimit the claim to only one item unless specifically stated to thecontrary in the claim. Further, when the language “at least a portion”and/or “a portion” is used the item may include a portion and/or theentire item unless specifically stated to the contrary.

What is claimed is:
 1. A method comprising: stitching a layer ofnon-crimped fibers together by bending an elastic fiber around thenon-crimped fibers; forming the layer of non-crimped fibers into a corepreform shape; and infiltrating the core preform shape with a ceramicmatrix to form a non-finished ceramic matrix composite component.
 2. Themethod of claim 1 further comprising: coating the non-crimped fibersprior to the infiltrating the core preform shape with a material atleast partially made from boron nitride.
 3. The method of claim 1further comprising: at least one of dissolving or removing by heatingthe elastic fiber from the preform prior to the infiltrating by exposingthe elastic fiber to at least one of a liquid, a gas or heat in avacuum.
 4. The method of claim 1 further comprising: processing thenon-finished ceramic matrix composite component to make a finishedcomponent that is operable in a gas turbine engine.
 5. The method ofclaim 1 further comprising: processing the non-finished ceramic matrixcomposite component with at least one of a machining, a grinding, asanding, and/or a coating operation.
 6. The method of claim 1, whereinthe non-crimped fibers are positioned substantially parallel to oneanother.
 7. The method of claim 1, wherein a diameter of the elasticfiber is less than a diameter of the non-crimped fibers.
 8. The methodof claim 1, further comprising: soaking the core preform shape in water;and drying the core preform shape in an oven.
 9. A method comprising:stitching a plurality of layers of non-crimped fibers, the non-crimpedfibers of each of the plurality of layers of non-crimped fibers beingstitched together by bending an elastic fiber around the non-crimpedfibers; forming the plurality of layers of non-crimped fibers into acore preform shape; and infiltrating the core preform shape with aceramic matrix to form a non-finished ceramic matrix compositecomponent.
 10. The method of claim 9, further comprising arranging theplurality of layers such that the non-crimped fibers of a first portionof the plurality of layers is positioned substantially orthogonally tothe non-crimped fibers of a second portion of the plurality of layers.11. The method of claim 9, further comprising stitching an adjacent pairof the plurality of layers of non-crimped fibers to each other bystitching the elastic fiber between the adjacent pair of the pluralityof layers of non-crimped fibers.
 12. A ceramic matrix compositecomponent for a gas turbine engine comprising: a plurality of layers ofnon-crimped fibers, wherein each layer includes a plurality ofnon-crimped fibers positioned substantially parallel to one another, anelastic fiber bent around the non-crimped fibers to stitch the layers ofnon-crimped fibers together to form a preform core shape; and a ceramicmatrix infiltrated into a portion of the preform core shape to form anon-finished component.
 13. The ceramic matrix composite component ofclaim 12, wherein the elastic fiber is made from at least one of apolymer material, an acrylic material, and a carbon material.
 14. Theceramic matrix composite component of claim 12, wherein the elasticfiber is configured to be at least one of dissolvable or removable byheating from the preform prior to infiltration of the ceramic matrix.15. The ceramic matrix composite component of claim 12, wherein thenon-crimped fibers comprise a mono filament and wherein a crosssectional diameter of the non-crimped fibers is between approximately 20and 300 microns.
 16. The ceramic matrix composite component of claim 12,wherein at least one layer includes a non-crimped fiber orientation thatis different from a non-crimped fiber orientation of an adjacent layer.17. The ceramic matrix composite component of claim 12, wherein thecomponent includes at least one of a static turbine vane and a rotatableturbine blade.
 18. The ceramic matrix composite component of claim 12,wherein a diameter of the elastic fiber is less than a diameter of thenon-crimped fibers.
 19. The ceramic matrix composite component of claim12, wherein at least two of the plurality of layers are arranged in afirst orientation and at least one of the plurality of layers isarranged in a second orientation which is angularly different from thefirst orientation.
 20. The ceramic matrix composite component of claim12, wherein a majority of the plurality of layers are arranged in aspan-wise orientation and a minority of the plurality of layers arearranged in a chord-wise orientation.